1. Field of Invention
The present invention relates to an active matrix electrooptical panel such as a liquid crystal panel having a thin film transistor (referred to TFT hereinafter) addressing-type panel, and to electronic appliances using the electrooptical panel.
2. Description of Related Art
FIG. 16 shows an active matrix liquid crystal panel having a plurality of pixel electrodes 9a provided in a matrix and a TFT switching element 30' for each pixel electrode. Scanning lines 3a and data lines 6a cross near each of the TFTs 30' and the pixel electrodes 9a are in electrical contact with a drain region of the TFTs 30' via contact holes 8 in a TFT array substrate. Each TFT 30' is constructed so that a channel region 1a' (the area indicated by hatch lines from the bottom to the left-top in FIG. 16) of a semiconductor layer 1a is controlled by a gate electrode 3a' extending from the scanning line 3a. The data line 6a, which supplies image signals, is put into electrical contact with the source region of the semiconductor layer 1a via a contact hole 5. Since the pixel electrode 9a can be provided on various films including wiring connections for the TFT 30', data lines 6a and scanning lines 3a, or on the interlayer insulation films for insulating the pixel electrodes 9a, the pixel electrode 9a is put into electrical contact with the drain region of TFT 30' via the contact hole 8 formed in an interlayer insulation film.
To obtain a high resolution liquid crystal panel, pixels in the display must be made smaller (i.e., finer) and very precisely. However, narrowing the pixel pitch L as shown in FIG. 16 to enable fine and precise image display by increasing pixel density or to compact the liquid crystal panel causes spaces between wiring lines that serve as non-opening regions to be narrowed. One important factor typically required for a liquid crystal panel is, on the other hand, increasing the brightness of the panel. Increased brightness can be realized by increasing the aperture ratio of the pixel, i.e., increasing the ratio of the opening region of the pixel to the image display region of the pixel. However, the TFT region, which includes wiring lines and switching elements for a pixel, serves as a non-opening region and when the pixel is made to be fine, the TFT region limits the extent to which the aperture ratio of the pixels can be increased. Accordingly, making the pixels fine results in narrowing of the distance between the contact holes 8 for contacting the pixel electrodes 9a with the TFT 30', and data lines 6a or scanning lines 3a , possibly causing fatal defects by forming short-circuits between the pixel electrodes 9a and respective wiring lines.